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Re: ldp-ISSUE-6 (User-defined simple types): Should LDBP say that any kind of user-defined simple data type is disallowed? [Linked Data Platform core]

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Fri, 21 Sep 2012 09:36:44 +0100
Message-ID: <505C271C.3060003@epimorphics.com>
To: public-ldp-wg@w3.org


On 21/09/12 00:27, Linked Data Platform (LDP) Working Group Issue 
Tracker wrote:
> ldp-ISSUE-6 (User-defined simple types): Should LDBP say that any kind of user-defined simple data type is disallowed? [Linked Data Platform core]
>
> http://www.w3.org/2012/ldp/track/issues/6
>
> Raised by: Erik Wilde
> On product: Linked Data Platform core
>
> i think we absolutely have to allow derived datatypes (not just the
XSD built-in simple types listed in section 4.1.9). if i am publishing
data with any kind of measurement data, of course, what i should do is
use a type that says that something is an integer, but that also is a
derived type that says that this is the length of something in meters.
or feet. or whatever else i am using. requiring XSD types only pretty
much disallows linked data to use the datatypes that may be at the very
core of a dataset, and pretty much every XML dataset i know defines its
own layered set of datatypes on top of the XSD basic types. i am
assuming that RDF datasets are not that different, and that data
producers have type systems much richer than just XSD's basic types.
>

Suggested slight rewording:

[[
i think we absolutely have to allow user-define datatypes (not just the 
XSD built-in simple types listed in section 4.1.9). if i am publishing 
data with any kind of measurement data, of course, what i should do is 
use a type that says that something is an integer, but also with a 
datatype that says that this is the length of something in meters. or 
feet. or whatever else i am using. requiring XSD types only pretty much 
disallows linked data to use the datatypes that may be at the very core 
of a dataset, and pretty much every XML dataset i know defines its own 
layered set of datatypes on top of the XSD basic types. i am assuming 
that RDF datasets are not that different, and that data producers have 
type systems much richer than just XSD's basic types.
]]

This changes "derived datatypes" to "user-defined datatypes" which 
matches the title of the issue.  It then covers the QUDT and Geo examples.

"derived datatypes" has a special meaning in XSD which is important here 
but it's not the whole story.

[[
Background:
Derived datatypes are restrictions of core XSD primitive datatypes.

See
   http://www.w3.org/TR/xmlschema11-2/#built-in-datatypes
for a picture.

xsd:positiveInteger is a derived datatype of xsd:integer.
and xsd:integer is a derived datatype of the primitive datatype xsd:decimal.

The example of "length in meters" is datatype defined outside the XSD 
definition (it adds the concept of the length unit).
]]

	Andy
Received on Friday, 21 September 2012 08:37:16 UTC

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